I have always used my external frame for packing out meat mainly because it's all I've ever had to use.
My internal framed packs are too small to even carry a quartered deer out but boned out is ok. But where do I put my gear if I only need one trip ? Some times I bungie/tie my badlands 2200 pack to my pack frame with good heavy duty game bags and then I can pack the meat out in the bags tied the the pack frame then bungie my pack onto to it. Last year I got lazy with a doe antelope and gut it, cut it in half, cut legs off at the knees and put each half in a bag and bungied to the pack frame and hauled it out about a mile or so. I didn't have my pack , just my rifle and binos, knife and saw. Bungied all to frame. I knew I was going to shoot one when I saw them and put on a loooong stalk so didn't take my pack. I would of if I didn't see what I was going after first. Just my experiences.